Glossary

A reference guide to bicycle terminology.

A

ABP (Active Braking Pivot) — Trek's suspension design that places the main pivot concentric with the rear axle to isolate braking forces.
Air Spring — A suspension spring that uses compressed air instead of a metal coil, allowing easy adjustment via a pump.
Anti-Rise — A suspension property describing how much braking forces affect suspension movement.
Axle Path — The arc or curve the rear axle follows as the suspension compresses and extends through its travel.

B

B-Tension Screw — An adjustment screw on a rear derailleur that sets the distance between the guide pulley and cassette sprockets.
Bar (Pressure) — A metric unit of pressure equivalent to approximately 14.5 PSI, used in tire and suspension pressure measurement.
Bar Sweep — The rearward angle of a handlebar from the clamp area to the grip ends, affecting wrist comfort.
Barrel Adjuster — A threaded cylindrical adjuster on a cable stop or derailleur that allows fine-tuning of cable tension.
Berm — A banked corner on a trail that allows riders to maintain speed through turns.
Bike Park — A resort or facility with purpose-built downhill trails, often with chairlift access.
Boost Spacing — A wider hub spacing standard — 110mm front, 148mm rear — allowing wider tire clearance and stiffer wheel builds.
Bottom Bracket Drop — The vertical distance the bottom bracket sits below the axle centerline, affecting cornering clearance and stability.
Bottom Bracket Drop — The vertical distance the bottom bracket sits below the wheel axle centerline.
Bottom Bracket Height — The height of the bottom bracket above the ground, affecting pedal clearance and center of gravity.
Bottom Out — When suspension reaches the end of its travel under a large impact, often felt as a harsh clunk.
Bottom Out Resistance — A feature of air springs that progressively increases resistance near the end of travel to prevent harsh bottom outs.
Brake Bed In — The process of transferring pad material to the rotor surface to achieve optimal braking performance.
Brake Contamination — Oil or other substances on brake pads or rotors that reduces braking effectiveness.
Brake Fade — A reduction in braking power caused by heat buildup in the rotors and pads during sustained braking.
Brake Lever Reach — The distance from the handlebar to the brake lever blade, adjustable on most modern levers for different hand sizes.
Brake Modulation — The ability to finely control braking force between fully released and fully applied.
Brake Rotor — The metal disc attached to the wheel hub that brake pads clamp onto to slow the bike.
BSA (British Standard) Bottom Bracket — The most common threaded bottom bracket standard, with 1.37-inch threads and 68mm or 73mm shell width.
Bunny Hop — A technique for lifting both wheels off the ground simultaneously to clear obstacles.

C

Cable Housing — The outer sheath that guides brake and derailleur cables, protecting them from dirt and damage.
Cable Tension — The tightness of a shift or brake cable, affecting actuation and feel.
Cadence — The rate of pedaling measured in revolutions per minute (RPM).
Casing a Jump — Landing short of a jump's intended landing zone, typically hitting the knuckle of the jump.
Cassette — A cluster of sprockets on the rear hub that provides the range of gears on a bike.
Center of Curvature — The point describing the curvature of the axle path as suspension moves through its travel.
Centerlock — Shimano's rotor mounting standard using a splined interface and lockring, offering quick and precise installation.
Chain Stretch — Wear elongation of a bicycle chain over time, causing poor shifting and accelerated sprocket wear.
Chainline — The alignment between the chainring and rear sprockets, affecting shifting performance and chain wear.
Chainstay Length — The distance from the bottom bracket to the rear axle, affecting climbing traction and maneuverability.
Cleaning a Feature — Successfully riding through a trail feature or section without putting a foot down or crashing.
Cleat — A metal or plastic fitting on the bottom of a cycling shoe that engages with a clipless pedal.
Clincher Tire — The most common tire type, with a separate inner tube and hooked bead that clinches onto the rim.
Clipless Pedals — Pedals with a binding system that clips into cleats on the bottom of cycling shoes.
Clutch Derailleur — A rear derailleur with a friction mechanism on the cage pivot to reduce chain slap and drop.
Coil Spring — A metal helical spring used in suspension forks and rear shocks, known for linear feel and low maintenance.
Compression Damping — Resistance to suspension compressing, controlling how quickly the suspension moves inward under impact.
Compressionless Housing — Brake cable housing constructed to resist lengthwise compression for more consistent brake feel.
Crank Length — The distance from the crank bolt center to the pedal axle center, affecting leverage and pedaling arc.
Cross 3 Lacing — The most common spoke lacing pattern where each spoke crosses three others between hub and rim.
Cross Chaining — Using extreme gear combinations that put the chain at a severe angle, causing accelerated wear and noise.
Cross Country Racing — A racing format involving laps on mixed terrain emphasizing fitness, climbing, and technical skill.

D

Derailleur Hanger — A replaceable aluminum tab on the frame that the rear derailleur bolts to, designed to break before the frame.
DOT Fluid — Glycol-based hydraulic brake fluid used by SRAM, Formula, and others. Hygroscopic — absorbs moisture over time.
Doubletrack — A wider trail or dirt road with two wheel ruts, often an old fire road or jeep track.
Downhill Racing — Racing format where riders descend a steep course as fast as possible, typically using chairlifts for uplift.
Drop — A feature where the trail ends abruptly and the rider becomes airborne before landing on a lower surface.
Dropper Post — A seatpost with a remote-actuated mechanism allowing the rider to raise and lower seat height on the fly.
Dual Compound Tire — A tire with a harder center tread for rolling efficiency and softer edge knobs for cornering grip.
Dual Ply Tire — A tire with two layers of casing fabric for increased puncture and sidewall protection, common in DH racing.
DW-Link — Dave Weagle's co-rotating twin-link suspension design used by Pivot, Evil, and others.

E

Effective Seat Angle — The actual angle from bottom bracket to saddle position, accounting for setback.
Effective Top Tube — The horizontal distance from the head tube to the seat tube, used to compare frame sizes across different designs.
Endo — A crash or maneuver where the rider goes over the handlebars, also called a front flip.
Enduro Racing — A format where timed stages are ridden downhill and untimed transfers are pedaled between stages.

F

File Tread — A tire tread pattern with small closely-spaced knobs optimized for hard-packed and dry conditions.
Fixed Gear — A drivetrain with no freewheel mechanism — the rear cog is directly connected to the rear wheel so pedaling is always required.
Flat Pedals — Simple platform pedals with pins for grip, used without special shoes.
Flip Chip — A small reversible hardware insert in a suspension link that allows geometry adjustments like BB height and head angle.
Float — The rotational movement allowed by a clipless pedal before the cleat releases, reducing knee stress.
Flow Trail — A purpose-built trail with smooth berms, rollers, and jumps designed for momentum and fun.
Folding Tire — A tire with a Kevlar bead instead of wire, allowing it to be folded for storage and reducing weight.
Fork Offset — The perpendicular distance between the fork's steering axis and the front axle centerline.
Freehub — The ratcheting mechanism on the rear hub that the cassette mounts onto, allowing coasting.
Freehub Body — The splined outer shell of the freehub that the cassette slides onto.
Freewheel — An older rear sprocket cluster that includes its own ratcheting mechanism, threading directly onto the hub.
Front Center — The distance from the bottom bracket to the front axle.

G

Gap Jump — A jump with open space between the takeoff and landing, requiring commitment to clear safely.
Gear Ratio — The mathematical relationship between chainring teeth and rear cog teeth, determining pedaling effort and speed.
GPS Computer — A handlebar-mounted device that tracks speed, distance, elevation, and route using GPS satellites.
Grips — Rubber or foam coverings on the handlebar ends that provide comfort and control.

H

Handlebar Rise — The height difference between the bar clamp area and the ends of the handlebar.
Handlebar Width — The total width of the handlebar, affecting leverage, control, and fit.
Hardpack — Firm, compacted trail surface that offers fast rolling and predictable traction.
Head Tube Angle — The angle of the head tube relative to the ground, affecting steering speed and stability.
Headset — The bearing assembly at the head tube that allows the fork to rotate for steering.
Heart Rate Monitor — A device that measures beats per minute during exercise, used to gauge exertion and fitness.
Hero Dirt — Colloquial term for perfectly conditioned soil that provides ideal traction in all conditions.
HG Freehub — Shimano's standard freehub spline pattern, compatible with most Shimano and SRAM cassettes up to 11-speed.
High Pivot — A suspension design with the main pivot placed high on the front triangle, paired with an idler pulley.
High Speed Compression — Damping that controls suspension movement during fast, sharp impacts like rocks and roots.
High Speed Rebound — Damping that controls how quickly suspension returns after a large, fast impact.
Hookless Rim — A rim without a hooked bead seat, requiring tubeless-specific tires and lower maximum pressures.
Horst Link — A four-bar suspension design with a pivot on the chainstay below the axle, used by Specialized and others.
Housing End Cap — A ferrule that fits over the end of cable housing to prevent fraying and ensure smooth cable movement.
Hub Flange — The flat circular part of a hub with holes for spoke heads.
Hub Shell — The outer body of a hub that the spokes attach to.
Hydraulic Disc Brake — A disc brake system that uses hydraulic fluid to transfer lever force to the caliper, offering powerful and consistent braking.

I

Idler Pulley — A small pulley used in high-pivot suspension designs to maintain chain length as the suspension moves.
Inner Wire — The cable that runs through housing to actuate brakes or derailleurs.
Instant Center — The theoretical pivot point around which a suspension system rotates at any given point in its travel.
Integrated Headset — A headset where the bearings sit directly in the head tube without cups, requiring precise frame machining.
Internal Rim Width — The measurement between the inner walls of a rim, directly affecting tire profile and volume.

K

Knobbly — Informal term for a mountain bike tire with pronounced tread knobs for off-road traction.
KOM (King of the Mountain) — The fastest recorded time on a Strava segment, awarded to the top male rider.

L

Leverage Ratio — The mechanical relationship between wheel travel and shock travel at any given point in suspension travel.
Limit Screws — Adjustment screws on a derailleur that set the maximum inward and outward travel of the derailleur cage.
Line — The chosen path through a trail feature or section.
Lined Housing — Cable housing with a low-friction inner liner to reduce cable friction and improve shifting or braking feel.
Linkage Driven — A suspension design where a linkage system drives the shock rather than connecting directly to the swingarm.
Loam — Dark, loose, organic soil that provides excellent traction and is highly sought after by mountain bikers.
Lock-On Grips — Handlebar grips that clamp onto the bar with a collar, preventing rotation without adhesive.
Lockout — A feature that firms up or completely locks suspension to reduce bob during climbing or road riding.
Low Speed Compression — Damping that controls suspension movement during slow, sustained forces like pumping and body movement.
Low Speed Rebound — Damping that controls how quickly suspension returns during slower, more controlled movements.

M

Manual — Riding with the front wheel lifted without pedaling, balancing on the rear wheel.
Mechanical Disc Brake — A disc brake actuated by a cable rather than hydraulic fluid, simpler but less powerful than hydraulic systems.
Microspline — Shimano's freehub standard for 12-speed cassettes with a 10-tooth smallest cog.
Mineral Oil — A non-hygroscopic hydraulic brake fluid used by Shimano and others, requiring less frequent replacement than DOT fluid.

N

Narrow Wide Chainring — A chainring with alternating narrow and wide teeth that mesh tightly with chain plates to prevent chain drop.
Negative Spring — A small air chamber that counteracts the positive spring at the beginning of travel to improve small-bump sensitivity.

O

Open Tread — A tire tread with widely spaced knobs that self-clean in mud and loose conditions.
Organic Brake Pads — Resin-compound brake pads that offer better initial bite and quieter operation but wear faster than sintered pads.

P

Pedal Bob — Unwanted suspension movement caused by pedaling forces, common in poorly tuned or designed suspension.
Pedal Platform — The surface area of a flat pedal that the foot rests on.
Platform Damping — A threshold of force required before suspension begins to move, reducing pedal bob without fully locking out.
Power Meter — A device that measures cycling power output in watts, used for training and performance analysis.
Preload — Initial tension applied to a spring to adjust the starting position and feel of suspension.
Press Fit Bottom Bracket — A bottom bracket that presses directly into the frame shell without threads, allowing larger bearing diameters.
Progression — The rate at which a suspension system becomes stiffer as it moves through its travel.
PSI (Pounds Per Square Inch) — A unit of pressure used to measure tire inflation and suspension air spring pressure.
Pump Track — A circuit of rollers and berms designed to be ridden without pedaling by pumping the terrain.

Q

Q-Factor — The distance between the outer faces of the crank arms, affecting pedaling stance width.
Quick Release — A lever-operated skewer that passes through hollow axle hubs to secure wheels without tools.
Quick Release Skewer — A hollow skewer with a cam lever that clamps through a hub axle to secure the wheel.

R

Radial Lacing — A wheel lacing pattern where spokes go directly from hub to rim without crossing, used on low-stress front wheels.
Reach — The horizontal distance from the bottom bracket to the top of the head tube, a key sizing measurement.
Rebound — The speed at which suspension returns to its extended position after being compressed.
Rim Tape — Tape applied to the inner rim bed to seal spoke holes for tubeless setups.
Rim Width — The internal or external width of a wheel rim, affecting tire fit, shape, and performance.
Rock Garden — A trail section covered in rocks of varying sizes requiring technical line choice and bike control.
Rocker Link — A pivoting link that connects the rear triangle to the shock, used to tune leverage ratios.
Roller — A smooth rounded mound on a trail that can be pumped for speed or jumped.

S

Saddle Height — The distance from the center of the bottom bracket to the top of the saddle, a fundamental bike fit measurement.
Saddle Setback — The horizontal distance the saddle sits behind the bottom bracket center.
Saddle Tilt — The angle of the saddle relative to horizontal, affecting comfort and power transfer.
Sag — The amount a suspension compresses under the rider's weight when sitting in a neutral riding position.
Seat Tube Angle — The angle of the seat tube relative to the ground, affecting pedaling efficiency and weight distribution.
Seatpost Setback — The offset of a seatpost that places the saddle rails further behind the seatpost clamp center.
Send It — Colloquial term for committing fully to a jump or challenging feature.
Single Chainring — A drivetrain setup with only one chainring at the front, relying on a wide-range rear cassette for gearing.
Single Speed — A bike with only one gear ratio, using a freewheel or fixed cog with no derailleur.
Singletrack — A narrow trail wide enough for only one rider, the primary surface of mountain biking.
Sintered Brake Pads — Metal-compound brake pads that offer longer life and better wet-weather performance but require more rotor wear-in.
Six Bolt Rotor — The most common rotor mounting standard, using six small bolts to attach the rotor to the hub flange.
Slick Tire — A tire with minimal or no tread pattern, used on smooth surfaces for reduced rolling resistance.
Spoke Count — The number of spokes in a wheel, affecting weight, strength, and aerodynamics.
Spoke Lacing — The pattern in which spokes are arranged between hub and rim, affecting wheel stiffness and strength.
Spoke Nipple — A small nut that threads onto the spoke at the rim, used to adjust spoke tension.
Spoke Tension — The tightness of spokes in a wheel, critical for wheel strength, trueness, and longevity.
Spring Rate — The stiffness of a spring, measured as the force required to compress it by a given distance.
Stack — The vertical distance from the bottom bracket to the top of the head tube.
Standover Height — The height of the top tube at its midpoint, relevant for fit and clearance when stopping.
Steerer Tube — The upper portion of the fork that passes through the head tube and is clamped by the stem.
Stem Length — The distance from the steerer tube clamp center to the handlebar clamp center, affecting handling and fit.
Stem Rise — The angle of a stem relative to horizontal, affecting handlebar height.
Stiction — Static friction in suspension seals that prevents smooth small-bump response, especially when cold.
Strava — A popular GPS activity tracking app used by cyclists and runners to record rides and compare segments.
Superboost — An even wider rear hub spacing of 157mm, used on some enduro and DH bikes for additional chainline clearance.
Switch Infinity — Yeti's unique suspension design using a sliding link that changes pivot location through the travel.
Switchback — A sharp hairpin turn on a trail, often on steep terrain, requiring slow speed and precise technique.

T

T47 Bottom Bracket — A threaded bottom bracket standard with a larger 47mm inner diameter, combining threaded reliability with press-fit bearing sizes.
Table Top — A jump with a flat top surface between the lip and landing, safer than gaps because it can be ridden flat.
Tapered Steerer — A steerer tube that is 1.5 inches at the lower bearing and 1.125 inches at the stem clamp for increased stiffness.
Technical Trail — A trail with challenging features like rocks, roots, steep sections, and tight turns requiring skill to navigate.
Threaded Bottom Bracket — A bottom bracket that threads into the frame shell, known for ease of installation and reduced creaking.
Threaded Headset — An older headset standard where the fork steerer tube has threads for adjustment, common on older bikes.
Threadless Headset — The modern standard headset where a stem clamps onto a smooth steerer tube and a top cap adjusts bearing preload.
Thru-Axle — A solid axle that threads through the fork or frame dropout and into the hub, replacing quick release skewers.
Tire Bead — The edge of a tire that seats against the rim, holding the tire in place. Can be wire or folding (Kevlar).
Tire Casing — The fabric structure of a tire, rated by threads per inch (TPI). Higher TPI = lighter and more supple.
Tire Compound — The rubber formulation of a tire tread, balancing grip, durability, and rolling resistance.
Tire Insert — A foam or rubber insert inside a tubeless tire that protects the rim from impacts and prevents burping.
Tire Pressure — The amount of air in a tire measured in PSI or bar, affecting rolling resistance, traction, and puncture resistance.
Tokens — Small plastic inserts placed inside an air spring to reduce volume and increase progression.
TPI (Threads Per Inch) — A measurement of tire casing density. Higher TPI casings are lighter, more supple, and more puncture resistant.
Trail — A geometry measurement describing the horizontal distance between the front axle and the steering axis contact point.
Trail Riding — General recreational mountain biking on natural or purpose-built trails.
Travel — The total distance a suspension system can compress, measured in millimeters.
Tread Pattern — The arrangement of knobs and voids on a tire surface, designed for specific terrain and conditions.
Tubeless — A wheel and tire setup without an inner tube, using a sealed rim and tubeless-ready tire with sealant.
Tubeless Sealant — Latex-based liquid inside a tubeless tire that automatically seals small punctures.
Tubular Tire — A tire with an inner tube sewn inside the casing, glued to a special rim. Used in road racing.
Two Finger Braking — The modern technique of using only the index and middle fingers on brake levers for better control.

U

Uplift — Shuttle service or chairlift that carries riders and bikes to the top of a descent.
Upsweep — The upward angle of a handlebar from clamp to grip ends, affecting wrist and shoulder position.

V

VPP (Virtual Pivot Point) — Santa Cruz's twin-link suspension design where counter-rotating links create a virtual pivot point.

W

Wheel Dish — The centering of a wheel rim relative to the hub flanges, necessary for proper alignment in the frame.
Wheel True — The process of adjusting spoke tension to eliminate lateral and radial wobbles in a wheel.
Wheelbase — The distance between the front and rear axles, affecting stability and handling.
Wheelie — Riding with the front wheel lifted while pedaling to maintain the position.
Wire Bead Tire — A tire with a steel wire bead, heavier and less expensive than folding tires but not foldable.

X

XD Driver — SRAM's freehub standard that allows 10-tooth smallest cogs, required for Eagle 12-speed cassettes.

Z

Zero Stack Headset — A headset design where bearing cups sit inside the head tube with only the bearing race visible.